JPH0462946A - Mounting method of ic chip on liquid-crystal display panel - Google Patents

Abstract

PURPOSE:To enhance the production yield of a liquid-crystal display panel by a method wherein, after the operation state of an IC chip has been confirmed, a resin for connection is heated to a hardening temperature to obtain a regular connection state. CONSTITUTION:A transparent electrode (ITO) is formed on a glass substrate 1; and electrode terminal parts 11, 12 for drive use are formed at its end. A liquid-crystal display panel 10 is manufactured by using two substrates of the above execution. Several tens of bumps 20 are formed on the rear of an IC chip 2 which is mounted on the electrode terminal parts 11, 12 for drive use. A lighting test of the liquid-crystal display panel 10 is first executed in a state that a resin 3 for connection use is semi-hardened and temporarily connected (in an electrically conductive state); and the operation state of the IC chip 1 is confirmed. That is to say, a mounting method composed of the following is used: it is confirmed that the IC is operated normally and that the bumps 20 are connected to prescribed positions; after that, the resin 3 for connection use is heated to a hardening temperature ; and a regularly connected state is obtained. Consequently, when it is found that the IC is not operated normally or that the bumps 20 are not connected to the prescribed positions, the IC chip 2 in a temporarily connected state is detached by using, e.g., a demounting tool 50 for exclusive use and is replaced.

Description

[Detailed Description of the Invention] [Summary] Regarding a method of mounting an IC chip on a liquid crystal display panel, the present invention relates to a method of mounting an IC chip on a liquid crystal display panel, and provides stability in mounting an IC chip in a chip-on-glass (COG) method and early removal of IC defects caused by connection. Depending on the quality of the LCD display panel.

With the aim of improving reliability and yield, we have developed an integrated circuit for liquid crystal display panels in which IC chips are directly mounted and connected to the drive electrode terminals on the glass substrate of the liquid crystal display panel using a connecting resin.
In the C chip mounting method, a lighting test is performed on the liquid crystal display panel in a temporarily connected state where the connecting resin is semi-hardened, and after confirming the operating state of the IC chip, the connecting resin is heated to a curing temperature. The method for mounting the IC chip on the liquid crystal display panel is configured so that the IC chip is brought into the final connected state.

[Industrial application field]

The present invention relates to a method for mounting an IC chip on a liquid crystal display panel having a high-density electrode terminal array, and particularly to an improvement in a method for mounting an IC chip in a chip-on-glass (COG) method.

In recent years, the development of display devices has been remarkable, and in particular, flat displays have rapidly become popular due to their thinness and light weight. Among them, liquid crystal display devices have a low driving voltage and are inexpensive, so they are being actively introduced into the field of office automation equipment such as personal computers and word processors.

Liquid crystal display panels used for these applications are required to display characters and graphics, so they must have large screens, many pixels,
As we move toward higher definition, the number of display line electrode terminals in LCD panels can reach several hundred or more, and issues related to connection with drive circuits, such as driver ICs, are becoming increasingly important. It's coming.

[Conventional technology]

Generally, a liquid crystal display device has stripe-shaped transparent electrodes (ITO: In2O3-3n02) formed on two glass substrates, with the picture electrode surfaces facing each other and perpendicular to each other.
Paste them together with an interval of approximately μm. And the above 2
When liquid crystal is injected into the gap created by two glass panels and a voltage is applied, the intersection of both striped electrodes becomes an optical switch due to the electro-optical effect of the liquid crystal and the polarizing plates placed on both sides, forming a pixel and changing the brightness and darkness. Display is performed.

The ends of the striped transparent electrodes constitute drive electrode terminals, which are connected to drive circuits as appropriate so that the intersections of both striped electrodes are driven and controlled during operation.

The currently widely used method for connecting the drive electrode terminals to the drive circuit is the TAB cable (Tape cable).
Auto-mated Bonding).

This is the so-called TAB method, but due to demands for larger screens, higher definition, and lighter weight of liquid crystal display devices, in the future, a method of mounting and connecting IC chips directly to the drive electrode terminals on the glass substrate, the so-called TAB method, will be adopted. C0G (Chip on Glass)
The trend is to move toward a mounting method.

Figure 4 shows an example of COG mounting of an IC chip on a liquid crystal display panel, where (a) is a plan view and (b) is an A-
It is A sectional view (partially enlarged view).

In the figure, IO is a liquid crystal display panel, for example, size 20
ITO on two glass substrates of 0 mm x 300 mm
A striped transparent electrode (not shown) is formed, and an alignment film (also not shown) is provided on top of the striped transparent electrode (not shown), and both striped electrodes are placed so that the alignment film surface is on the inside so that an X-Y matrix intersection is formed. The peripheral edge of the substrate is sealed with a spacer sandwiched between the substrates, and liquid crystal is injected into the gap formed between the substrates, and the area formed by the many intersections of both striped electrodes is Configure the display surface. Both glass substrates have their respective ends protruded, and drive electrode terminal portions 11 (stripe electrode side) and 1
2 (power supply/signal line side) is formed.

2 is a driving IC chip with bumps 20. For example, gold bumps are formed. The driving IC drives the striped electrodes by grouping them into groups of several tens to 100 or more.

4 is, for example, a flexible printed board on which a wiring pattern 40 for power and signal lines is laid.

The connection between the IC chip 2 and the drive electrode terminal parts 11 and 12 is made by covering the bumps 20 with a connecting resin 3°, for example, UV curing resin (or thermosetting resin), as shown in FIG. After coating, for example, IC chip 2
While applying pressure from above, ultraviolet rays are irradiated from below the glass substrate l to cure the UV curing resin, electrically and mechanically connected, and lighting tests and other tests are performed.

[Problem to be solved by the invention]

However, in the conventional IC chip 2 mounting method, the connection resin 3. For example, when performing a lighting test after the U■ hardening resin has hardened and the connection has been completed, the IC chip 2
was found to be defective.

Or, even if there is a defect in the connection, the IC chip cannot be replaced, and if it is forcibly removed, the drive electrode terminal parts 11 and 12 will be destroyed, and in either case, the entire expensive liquid crystal display panel will be defective. There was a serious problem that caused a large amount of waste, and it needed to be resolved.

[Means for solving the problem] The above problem is solved by using the connection resin 3 on the drive electrode terminal portion 11.12 on the glass substrate l of the liquid crystal display panel IO.
In a method of mounting an IC chip on a liquid crystal display panel in which a chip 2 is directly mounted and connected, a lighting test is performed on the liquid crystal display panel IO in a temporarily connected state in which the connecting resin 3 is semi-hardened to check the operating state of the IC chip 2. This problem can be solved by a method of mounting an IC chip on a liquid crystal display panel in which, after confirmation, the connection resin 3 is raised to a curing temperature to bring it into the final connection state.

[Effect]

According to the method of the present invention, connecting resin 3. For example, first, a lighting test is performed on the liquid crystal display panel 10 in a temporarily connected state where the thermosetting resin is semi-cured (in an electrically conductive state), and the operating state of the IC chip 2 is confirmed.
After confirming that the IC operates normally and that the bumps 20 are connected to the predetermined positions, the connection resin 3 is raised to a curing temperature to bring it into the final connection state. If it is found that the IC chip 2 does not operate normally or that the bump 20 is not connected to the predetermined position, the temporarily connected IC chip 2 can be removed and replaced using a special removal tool 50, so the LCD panel IO failures are greatly reduced.

〔Example〕

First, the size is 200 mm x 300 mm and the thickness is 1
A 1 mm transparent glass substrate is used, and In2O is placed on it.
A striped transparent electrode (ITO) made of a mixed oxide of -3nO2 is formed. The electrode pitch of the driving electrode terminal portions 11 and 12 formed at the ends thereof is 100 μm, and the pitch of the electrode terminals is approximately 50 μm. A liquid crystal display panel IO is manufactured using the above two substrates according to a conventional method.

The IC chip 2 mounted on the driving electrode terminal portion 11.12 is a dedicated driver I for driving the liquid crystal display panel.
For example, several tens of Au-coated bumps 20 are formed on the back surface of C, and the size of the bumps 20 is, for example, about 30 μm square and about 7 μm high.

An epoxy-based thermosetting resin was used as the connection resin 3, which was coated to cover the bumps 20, and then heated while applying pressure from the top surface of the IC chip 2, for example, 20 kg/cm2, to make the connection. Such pressurization and heating may be performed using, for example, a known wedge-type pulse heater.

In order to find out the relationship between connection resistance, heating temperature, and heating time, samples for connection resistance measurement were prepared in advance in the same shape as the beams, and measurements and evaluations were conducted while changing various conditions.

FIG. 1 is a diagram showing the relationship between connection resistance and heating temperature, with connection resistance plotted on the vertical axis and heating temperature plotted on the horizontal axis.

The pressurization is 20kg/cm2. The heating time was a constant value of 10 seconds. That is, the connection resistance rapidly decreases when the temperature reaches 160°C, and reaches a desirably low value above 170°C. In addition, A in the figure indicates whether or not the IC chip can be removed at each heating temperature by ○ and ×, where ○ indicates that it is removable and × indicates that it is not removable. On the other hand, B also indicates the presence or absence of air bubbles in the connecting resin 3.
and ×, ○ indicates no bubbles,
× indicates that bubbles remain without being removed. Since the presence of air bubbles in the connecting resin layer reduces the connection performance, it is a preferable condition that the air bubbles are sufficiently removed. As can be seen from the figure, if the heating temperature is 180° C. or lower, the IC chip can be removed, and if the heating temperature is 180° C. or higher, air bubbles can be sufficiently removed.

FIG. 2 is a diagram showing the relationship between connection resistance and heating time, in which the vertical axis represents the connection resistance and the horizontal axis represents the heating time.

In addition, the pressurization is 20 kg/am2. The heating temperature was kept at a constant value of 180°C. That is, the connection resistance rapidly decreases after 10 seconds, and becomes a constant low value after 15 seconds. Further, A in the figure indicates whether or not the IC chip can be removed at each heating time using ○ and ×. ○ indicates that it is removable, and × indicates that it is not removable. On the other hand, B shows the presence or absence of air bubbles in the connecting resin 3 by indicating the presence or absence of air bubbles in the connecting resin 3 using O and ×. ○ indicates that there are no air bubbles, and × indicates that air bubbles remain without being removed. . As can be seen from the figure, if the heating time is 10 seconds or less, the IC chip can be removed, and if the heating time is 10 seconds or more, air bubbles can be removed sufficiently.

From the measurement results of the above examples, the conditions for temporarily connecting the IC chip with the epoxy thermosetting resin used in this example are a heating temperature of approximately 180°C, a heating time of approximately 10 seconds, and a pressure of approximately 20 kg/cm. It can be seen that am2 is sufficient.

Note that the above temporary connection conditions are for the epoxy thermosetting resin used in the examples, and are therefore not limited to these, and may be similarly measured and evaluated depending on the type of connection resin 3 used. Then, the optimum temporary connection conditions can be determined.

As mentioned above < After the temporary connection of the IC chip 20, conduct a lighting test and other necessary tests, and if normal operation is confirmed, the connection resin 3 used is normally cured and connected.

For example, in the case of the epoxy thermosetting resin of the above embodiment, the main connection may be performed at a heating temperature of about 190° C., a heating time of about 20 seconds, and a pressing force of about 20 kg/cm 2 .

On the other hand, if normal operation is not obtained in a lighting test or the like after the temporary connection of the IC chip 20, the IC chip may be replaced using a removal tool, which will be described later, and then mounted using the same procedure.

FIG. 3 is a diagram showing an example of a tool for removing temporarily connected IC chips. In the figure, reference numeral 5 shows the external appearance of the IC chip removal tool, and at its lower end there is a metal frame-shaped body 50 that fits into the IC chip 20, and a heater 51 connected to the frame-shaped body 50. For example, a pulse heater is provided. The heater 5I is connected to a power control section (not shown) through an electric wire 52. There is a handle 5 on the top of the heater 51.
3 is provided.

If there is an IC chip that needs to be removed for a lighting test or the like, the frame 50 of the removal tool 5 is removed from the IC chip.
For example, in the case of the epoxy thermosetting resin of the above embodiment, the heating temperature is 140 to 1.
By heating the IC chip to 45° C. and turning the handle 53, the IC chip can be easily removed while being gently rotated.

By applying the method of this embodiment, the number of defects associated with the mounting of IC chips was reduced to about 1/10 compared to the conventional method, and as a result, the number of defects in liquid crystal display panels was significantly reduced.

The above-mentioned embodiments are merely examples, and the materials used, connection curing conditions, combinations thereof, and configurations of each part may be optimized as appropriate, as long as they comply with the spirit of the present invention. It goes without saying that you can use it selectively.

〔Effect of the invention〕

As explained above, according to the present invention, the connecting resin 3. For example, a thermosetting resin is first placed in a semi-cured, temporarily connected state (
conducting a lighting test on the liquid crystal display panel 10 (in an electrically conductive state) to check the operating state of the IC chip 2;
In other words, after confirming that the IC operates normally and that the bumps 20 are connected to predetermined positions, a mounting method is used in which the connection resin 3 is raised to a curing temperature to bring it into the final connection state. If it is found that the IC does not operate normally or that the bump 20 is not connected to the predetermined position, the temporarily connected IC chip 2 can be removed and replaced using a special removal tool 50, for example. The manufacturing yield of the liquid crystal display panel 10 is greatly improved, which greatly contributes to improving the quality and lowering the price of liquid crystal display devices.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between connection resistance and heating temperature, Figure 2 is a diagram showing the relationship between connection resistance and heating time, Figure 3 is a diagram showing an example of a tool for removing temporarily connected IC chips, and Figure 4 is a diagram showing the relationship between connection resistance and heating time. The figure shows an example of COG mounting of an IC chip on a liquid crystal display panel. In the figure, l is a glass substrate, 2 is an IC chip, 3 is a connection resin, 4 is a flexible printed board, 5 is a removal tool, 10 is a liquid crystal display panel, 11 and 12 are drive electrode terminals, and 20 is a bump. be. non-zero≦silence (compensation)

Claims (1)

[Claims] A liquid crystal display in which an IC chip (2) is directly mounted and connected to drive electrode terminal portions (11, 12) on a glass substrate (1) of a liquid crystal display panel (10) using a connecting resin (3). In the method for mounting an IC chip on a display panel, a lighting test is performed on the liquid crystal display panel (10) in a temporarily connected state in which the connecting resin (3) is semi-hardened, and the IC chip (2) is
) After confirming the operating state of the connecting resin (3), the connecting resin (3) is raised to a curing temperature to bring it into the final connected state.